Bottlehead Forum
Bottlehead Kits => Mainline => Topic started by: ALL212 on March 25, 2016, 01:17:23 PM
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Ok...I'm in. Been pondering the Mainline for some time and the sale has pushed me over the edge.
I know it doesn't come with BH upgrades but I'm sure there are those of you who have built this thing and have some good ideas. I have yet to build a kit and keep it stock. I have no intention of changing that with this kit.
I'm in no hurry, would like to ponder upon this and get it right.
What say you?
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I normally get BH notifications but not this Mainline one. As Doc's "check you mail" post doesn't have "Reply" box I couldn't comment there. :(
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Sometimes it takes a while for the mail to be distributed. Here is the content of the email:
It's Mainline March! From now through March 31st you can order our premium Mainline headphone amp kit and get a whopping $200 discount by using the coupon code published below.
mainlinemarch
To sweeten the deal we found another batch of the rare and exceptionally effective IERC tube shields, and we will include a pair with every Mainline kit order until they run out. The awesome sounding 6C45pi tube used in the Mainline is a hot little sucker and these shields should extend their useful lifetime by 10-15%.
Use the coupon code mainlinemarch when you check out to get this special discount. Time to manufacture and ship will be our standard 4 or so weeks. Kits are shipped in the order that orders are received - order sooner, get it sooner.
Join us April 30th at Bottleheadquarters on beautiful Bainbridge Island for another great Seattle Head Fi user group meet. These meets are a fantastic way to sample lots of cool headphones and headphone amps, and meet like minded headphone lovers. Everyone is encouraged to bring their favorite headphone rig if you have one, or just bring hungry ears if you don't!
Also in April we will be releasing a super quiet DC filament supply for the Stereomour II, along with our superb sounding stepped attenuator upgrade as used in our premium BeePre preamp kit. Watch for those to come out in a couple of weeks.
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I love my Mainline, now fed by a Shiit Gungnir Multibit.
All I did was swap in some Auricap XOs in place of the stock parafeed caps
My build here: http://bottlehead.com/smf/index.php?topic=7463.0
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Some thoughts - not necessarily unique to me.
Replace the .1 and 10 uf film caps.
Put a choke in place of the 230 ohm resistor.
If I can find room use a full film cap in place of the 100uf PS cap.
Tip the other PS caps with small films.
I like 6SN7's - any good reason to use one in place of the 12AU7? Will the circuit support this? I know I have to modify the hole and wiring.
Any other things you folks have done to this beast?
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I'm trying to resist this one. I already have a S.E.X. and a Crack-A-Two-A. And I just bought an Eros and a new TT. But I did just do my taxes, and have a nice refund coming.....
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I plan on buying a Mainline this year, and this is a smoking deal - it just unfortunately is not the right time for me to be able to buy it.
When I read the email it depressed me the entire day haha.
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Who am I kidding? I have no willpower. Plus, I did well enough on my taxes to buy two Mainlines, and I only bought one. So I'm saving money! ;D
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Thanks so much to everyone who is taking advantage of this deal. I happen to be particularly proud of this amp and it's nice to see so many people ordering one.
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Replace the .1 and 10 uf film caps.
Yes, though I wouldn't spend much on the 0.1uF caps.
Put a choke in place of the 230 ohm resistor.
Not a great idea. The shunt regulated power supplies make a power supply choke pretty pointless. Also, these need to be mounted on a different axis than the power transformer and output transformers, which I have yet to see done successfully.
If I can find room use a full film cap in place of the 100uf PS cap.
The hybrid shunt regulated power supply places great impedance between the power supply and the signal path, so replacing these capacitors with film capacitors is not a great expenditure of effort, and not all that easy since the power supply is PC board mounted.
I like 6SN7's - any good reason to use one in place of the 12AU7? Will the circuit support this? I know I have to modify the hole and wiring.
The 6SN7 draws twice the heater current of the 12AU7, which will place additional thermal load on the low voltage regulator. PJ would have a better record of the thermal overhead available with this particular power supply, but I don't believe it's advisable.
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Thanks PB! I had some evil ideas that I think I can just put aside now. Really looking forward to this kit. And... probably a classic rabbit hole. I'm thinking sometime in the future a pair of HD-800's now to go with this. ;D
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PB is right. The Mainline uses the power transformer originally designed for the Eros, so the transformer is pretty much operating at its limits with the stock tube complement.
The 12AU7 is used as the hybrid shunt regulator. The regulator performance is dominated by the 431 chip, so using different tubes should have little or no audible effect.
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"I know it doesn't come with upgrades"
It's our top line headphone amp kit. The whole circuit as it stands is an upgrade. My suggestion is spend the effort making it look however you think it should look to satisfy your taste rather than modifying the circuit. It's been pretty carefully thought out.
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You will get more out of swapping to a high grade balanced HP cable than changing the shunt regulator tube. Hell, the interconnect qualities are easily revealed by this amp.
IMHO, its just fine. The only thing left to do is to pick your colouration of choice. Changes are likely to be minute but with a high expense. Those changes may be thought to be towards improvement, but the reality is they are small enough generally you could con yourself in into endless circles.
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Woohoo!! Got the shipping notification today. Unfortunately, I'll be on deployment until October, but at least I've got something to look forward to. Thanks for the sale, Doc!
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You will get more out of swapping to a high grade balanced HP cable than changing the shunt regulator tube. Hell, the interconnect qualities are easily revealed by this amp.
IMHO, its just fine. The only thing left to do is to pick your colouration of choice. Changes are likely to be minute but with a high expense. Those changes may be thought to be towards improvement, but the reality is they are small enough generally you could con yourself in into endless circles.
Mine's here!! Much work to do before assembly but...
I've already got my own HP cable, will going from 1/4" to the XLR improve things? Can Senn HD 650's use an XLR? I can make the cable, that's not the problem. I'm just not familiar with the XLR and any advantage it may have.
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XLR would seem to make a difference to me. I decided to go with Moon Audio rather than possibly be disappointed with a first time DIY project. It could be the cable is imparting some of the improvement over stock. Actually I have no doubt that is the case. As for XLR/Balanced. For me, I've gone back the single ended a couple times for testing something, but so far its never stayed that way. YMMV.
The 650 can be balanced very easily. The connectors are common and easily soldered. See ebay for a world pre-fab ones.
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It's in - and here's a start.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4248_zps6rbxbiea.jpg&hash=ce22e7ee7355f2e4955ec5aea70c3f903c9fdd76) (http://s905.photobucket.com/user/all212212/media/DSC_4248_zps6rbxbiea.jpg.html)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4246_zpsr5xlfpxl.jpg&hash=6a82df7702e58e135ec31403cbc80122bab71c8d) (http://s905.photobucket.com/user/all212212/media/DSC_4246_zpsr5xlfpxl.jpg.html)
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It's in - and here's a start.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4248_zps6rbxbiea.jpg&hash=ce22e7ee7355f2e4955ec5aea70c3f903c9fdd76) (http://s905.photobucket.com/user/all212212/media/DSC_4248_zps6rbxbiea.jpg.html)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4246_zpsr5xlfpxl.jpg&hash=6a82df7702e58e135ec31403cbc80122bab71c8d) (http://s905.photobucket.com/user/all212212/media/DSC_4246_zpsr5xlfpxl.jpg.html)
I was just thinking the other day its been a while since there have been some new Mainline build pics enjoy the build. ;D
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Update:
Final output cap is 3x 30uf Solen film caps. Couldn't find room for a 100uf. These three measure closer to 100uf than the stock cap did.
Choke in place of the 270 ohm resistor.
Mogami wire will be used as much as possible.
Sound damping material on the plate - takes some boing out.
Voltage checks on the PS went just fine. So far...so good.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4510_zpsjspzhhxj.jpg&hash=932b1b3e6c13778cc0916a74530c682d54efbdea) (http://s905.photobucket.com/user/all212212/media/DSC_4510_zpsjspzhhxj.jpg.html)
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Looks stunning so far!
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Is the choke you used in place of the 270 ohm resistor the Triad C7X I have a couple in my parts box and was wondering?
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Very tidy build. I hope i am wrong about this, but i don't like the look of that choke so close to the output transformer. It may work fine, but i wouldn't be surprised if it created a lot of noise on that channel..
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Is the choke you used in place of the 270 ohm resistor the Triad C7X I have a couple in my parts box and was wondering?
Yes, it is - and it is an experiment. If I get some noise it should be an easy thing to just pull it and put the resistor back in. That's one of the reason's I decided to try it - easy access.
And I'm on temporary hold. One of the volume switches is missing one bottom lug so that's on the way back to BH land so I can get a new one.
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Very tidy build. I hope i am wrong about this, but i don't like the look of that choke so close to the output transformer. It may work fine, but i wouldn't be surprised if it created a lot of noise on that channel..
Its core is oriented at 90 degrees to the output transformer, which should be helpful in terms of noise mitigation. This is hypothetically a much better place to put the choke compared to mounting it above one of the output transformers.
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Starting the fine and course volume control soldering really needs a warning label:
NO COFFEE!!!
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4539_zpsq6wcdstw.jpg&hash=3cc9f9dc1af3dba2c549a669491909f7ab5a92ad) (http://s905.photobucket.com/user/all212212/media/DSC_4539_zpsq6wcdstw.jpg.html)
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Very clean build! Can't wait to start building mine. :)
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Impedance switching is complete.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4552_zpshoyiyj8b.jpg&hash=5eb3cf2dcd8bb8b98235b4202379aacef61df74c) (http://s905.photobucket.com/user/all212212/media/DSC_4552_zpshoyiyj8b.jpg.html)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4554_zps3sxvcuxx.jpg&hash=1dc80ce9698c8f0239a15882cdcdd6d258e912c4) (http://s905.photobucket.com/user/all212212/media/DSC_4554_zps3sxvcuxx.jpg.html)
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Actually, the coil axis of the choke is the same as the output transformer, so there may be some hum coupling. Not easy to predict the magnitude though.
You can listen to the speaker to determine whether the noise is acceptable, and whether it is noticeably different from the other channel.
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I have some aluminum tape - if I wrap the choke in that do you think it would do anything at all?
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No, aluminum is not magnetic.
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I meant as shielding - just wrap that sucker up with aluminum tape and ground one end.
Still not good?
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So does PJ. You would potentially need magnetic shielding for what we are talking about with this choke (coupling), not electrostatic. That means mu metal, molyperm, steel, soft iron, etc.
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AHHH!!!! sry....
I think we'll just use plan A - if it hums either find the words or remove it.
Output wiring:
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4564_zpswesweiru.jpg&hash=9bd2d934d2dfa275efc5ff52c4af189770c86d08) (http://s905.photobucket.com/user/all212212/media/DSC_4564_zpswesweiru.jpg.html)
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Got home from deployment a few days ago, and I finished the Mainline yesterday. Doc, you nailed it with this one. First track I listened to was Pink Floyd - Echoes. When that crescendo started building in the 15-20 minute mark, I had the biggest s**t-eating grin on my face.
I think my headphone system has finally reached end-game status. Thanks BH!
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Wow Nick, thanks so much for the kind words! And thanks for your service!
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Answer to the question:
A Saint!
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Rocketman248, thanks for your service. Much appreciated!
Next step is board mounting. Thought I'd throw this in before that starts.
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4573_zpsycx0s6w8.jpg&hash=2e4aae0bc0deec9da65cced1a4d4da5843d4a8a1) (http://s905.photobucket.com/user/all212212/media/DSC_4573_zpsycx0s6w8.jpg.html)
If everything checks out this could be done tomorrow.
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It almost checked...HELP!!
Resistance checks all good.
Initial voltage checks all good but the inside set of LED's on the A side came up slowly. Turned it off and realized I needed to set the voltages.
Terminal 20 is at 220v and the inside LED's (closest to the OT-3's) are not lit. The other pair are lit. It will not adjust.
The other channel is perfect - adjusts just fine.
I put in a new 12AU7 and switched the other tubes to the other sides. All heaters glow.
Remeasured volts.
KReg on A side is 3.8 volts - everything else is per spec.
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What are the OA, IB, and OB voltages on the bad side?
Does OB change when you adjust the blue trim pot?
-PB
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Bad side Good side
0A - 220 220
1B - 220 220
0B - 220 145
OB does not change on bad side. OB does change on good side.
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I did have two minor issues while building it. The first was during the power supply tests. I kept getting around 3.5 volts on both the 6.3v pads and the 275v pads. I rechecked everything, reflowed every joint. Racked my brain for a while, and ended up just going to bed. I took a look at it the next morning, and realized I was trying to measure AC volts on DC test points. There's a slight typo in the manual on Page 38. On the second step from the bottom, it says "You should see around 6.3VAC on your meter." I was reading quickly, and it didn't even click in my head that everything else on that page, and even printed on the board said DC. There's a lot to be said for the whole "Looking at things with a fresh set of eyes" thing. ::)
The other issue is with the coarse attenuator. When I first finished it, all of the resistance and voltage checks were spot on, but I was only getting audio on the right side. It didn't change with volume, and it was the same on both inputs. I checked everything in the output path, touched up a few questionable solder joints, and tried swapping tubes. Still no joy. Then, while listening, and adjusting the coarse attenuator, the sound came back to both ears. That's when I discovered that there was a slight play in the shaft on that attenuator. Looking at it closely, the swiper on the top side of the switch moves with the shaft, and is likely losing contact when I wiggle the shaft. I tried tightening the contacts by pushing on them with a toothpick, but it didn't change anything. I'm not too worried about it though. If I move the knob slightly to the front of the chassis, it works just fine. Someday, I might look at replacing it, but I'm not in a hurry.
Aside from those two issues, it was a fairly easy build, and it sounds great! I hope you get yours working soon, ALL212!
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Bad side Good side
0A - 220 220
1B - 220 220
0B - 220 145
OB does not change on bad side. OB does change on good side.
Can you confirm that the R1 resistors on the offending side are in the correct places? They are pretty easy to swap, and can cause anomalies like this.
Additionally, the center leg of those MJE5731A's can take a lot of heat to solder well. If one is not well soldered, you will also get this type of behavior. Shorts are another potential cause of this, and the most likely place for this would be on the solder joints for the PN2907 on the "B" portion of the high current C4S.
-PB
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R1's are good, board completely reflowed, no shorts AT THE BOARD!
Just before putting it back I put the magnifier on the socket. I had a cutoff shorting 5 to 6.
I have the same results at the board after this but what may have died by shorting pins 5 and 6 at the socket?
Would I be safe by reversing the outside boards? Or could I blow something else up in the process?
Sneak peak:
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi905.photobucket.com%2Falbums%2Fac253%2Fall212212%2FDSC_4582_zpsb0kjmaew.jpg&hash=c346bacc71ac36827b44e4ea955f69ee4eebbb4c) (http://s905.photobucket.com/user/all212212/media/DSC_4582_zpsb0kjmaew.jpg.html)
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I'm making a new thread for the troubleshooting...
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Thanks to the BH crew all is well - or almost. The fine volume control is one click off so I have max volume at -7.5 position and no volume change at the 0. Fixable but I'm almost liking it. I can be at minimum attenuation on fine and with one click go to the maximum attenuation. Got to spend some time thinking through this...
Converted my MrSpeakers Alpha Prime's to a balanced connection. Almost did the HD650's but then I wouldn't be able to play them on the B.A.Crack. With the S.E.X. going to the office I don't have anything else to play the MrSpeakers (low impedance) on anyway. Not sure if there is any difference - maybe a bit more L/R separation but nothing major that I can hear.
I think that's the end of this story. But... Now that I've seen what BH can do with headphones I'm thinking of replacing the Reduction with an Eros.
Thanks BottleHead for another great amp!